Heat Pump Electrical Problem - Need Electrical experts

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J

jbilliel

Well-known member
May 5, 2020
57
Connecticut
Team - I know enough to be dangerous, but I need another set of eyes on this. I have a aquacomfort heat pump. The pump is 4 years old and after starting it up today for the first time I noticed that the compressor is kicking on, but the Fan is not. I gave it a love tap and then it started turning. I went back out there a little while later and it stopped running again

I checked the capacitor and there is no short. I don't have a way to test the discharge of the capacitor, but it starts the compressor fine.

So I pulled followed the wiring on the fan and this is what there is:

5 wires to the motor:
ground
white - power from the relay
black - from the main power terminal coming into the unit
common - from the capacitor
fan - from the capacitor

here are the ohms readings

  1. There are no dead shorts to ground on any of the wires
  2. white to common - 0 ohms [This is the culprit, correct?]
  3. white to run - 56.4
  4. fan to common - 56.3
Given #2 gave me a short, the fan is toast, correct?
 
Last edited:
Discharge the capacitor by shorting the terminals with a piece of wire, a screwdriver across both sides, etc., not your finger.
Capacitors are inexpensive ($10.00 - $30.00) and one of the most common reasons the fan on an HVAC system (which your heat pump is) don't run. Give it a try before replacing the fan motor ($150.00 and up).
 
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Is to combo capacitor, meaning there’s a COMMON, FAN, and HERM connection? Herm is the compressor. You have to test all sides of the cap. One could be done and the other could be dead.
 
Unless you have a meter with a capacitor tester on it, you can’t really know for sure if it’s good. It doesn’t take much sag on a capacitor for it to stop working. The only other way to test them is to monitor the peak voltage at startup (again, you need a good meter for that with a min/max/hold feature) and then do some quick math to back out the capacitance. Obviously you have to be really safe around capacitors as their peak voltages can be quite high and you’ll get taze’ed if you do it wrong.

Swapping a cap is the easiest way to know.
 
JoyfulNoise said:
Unless you have a meter with a capacitor tester on it, you can’t really know for sure if it’s good. It doesn’t take much sag on a capacitor for it to stop working. The only other way to test them is to monitor the peak voltage at startup (again, you need a good meter for that with a min/max/hold feature) and then do some quick math to back out the capacitance. Obviously you have to be really safe around capacitors as their peak voltages can be quite high and you’ll get taze’ed if you do it wrong.

Swapping a cap is the easiest way to know.
Click to expand...
Sounds like a plan. If the cap doesn't do it, I will then go about replacing the fan.
 
jbilliel said:
Sounds like a plan. If the cap doesn't do it, I will then go about replacing the fan.
Click to expand...

It’s unusual for fan motors to die. If the fan spins freely and easily and there’s no shorts to ground on the coil, then it’s unlikely it’s the fan.

I would look at the contactor next. They are mechanical and if anything looks charred or burnt, replace the contactor. They take a beating every time the unit switches (just like the capacitor does) and it’s not unusual for those to burn out or start acting funky.
 
And check all the wiring harnesses … rats and critters LOVE to chew up wiring … it’s like Twizzlers to them …
 
Agreed with all the other comments, just to add a bit ... A digital multimeter that includes a capacitance range can be had for as low as $15 from regular places like harbor freight, amazon, temu. Can be a nice addition to your toolkit. A little more on safety... Wear glasses, and preferable to run a couple alligator leads away from the cap so you can toss a towel over the cap before discharging - in case it blows up. Then disconnect capacitor wires from cap terminals before testing. We used to blow them up from time to time in the motor shop, usually when charging but sometimes when discharging. I don't think the voltage can rise on them past the line voltage (eg 230) but it's plenty to tase you well. Injuries seldom came from the current passing through you because it's momentary. The injuries usually come from your reaction - slamming an arm or other body part into a wall, sticking yourself in the face or eye with a meter probe, etc. The harbor freight example: https://www.harborfreight.com/elect...multimeter-with-audible-continuity-59410.html
 

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